In the case of process controls for a continuous process, such as sheet forming processes, product quality parameters are focused on the period of time in which a particular “grade” of product is produced. A “grade” identifies a set of product specifications, such as sheet weight, sheet caliper, sheet brightness, and sheet color, for example. However, after a period of time, it may be desired that the specifications of the product, such as the sheet, be changed. The process in which the process line, which is initially configured to produce sheets of one specification, is transitioned to produce sheets of another specification is referred to as a grade change or operating transition. The grade change or operating transition is carried out by a transition control system that is interfaced with the various control systems. Specifically, the transition control system automates the operational set points of various functional components of the continuous process to ensure the product is produced in accordance with the new product specification identified by the grade change or operating transitions and that the process is achieving the desired grade change or operating transition.
While steady-state control processes are well-established and key performance indicators (KPI) are available to monitor their operation, such key performance indicators provide inadequate performance data when used to quantify the performance of operating transitions of a continuous process. For example, one manner for quantifying the performance of an operating transition or grade change is by monitoring the transition time required to complete the transition from one grade to another. However, transition time provides inadequate performance data and does not provide a complete and/or accurate assessment of the overall performance of the operating transition. Furthermore, because a continuous process requires producing products, such as sheets, that during the operating transition do not meet final production specifications, a substantial amount of production time and product waste can occur if the operating transition is not carried out in an optimized manner.
Therefore, there is a need for a system and method that generates a set of indices to quantify operating transition or grade change performance of a continuous process. In addition, there is a need for a system and method that generates multiple normalized performance indices associated with various parameters of the continuous process that take place during an operating transition or grade change, to enable comparison of grade change performance between multiple process lines. Furthermore, there is a need for a system and method to quantify the performance of one or more specific portions of a continuous process during the operating transition to readily identify specific portions of the process that are not attaining desired performance levels.